Human speech is more than simply the spoken words. It is also about how those words were spoken; audio signals resulting from, accompanying, and/or utilized in place of spoken words; and even the identity of the speaker who spoke them. In other words, a lot of human communication takes place in the non-semantic characteristics of a speaker's speech and speech patterns. The speaker's emotions add layers of contextual connotations that influence a listener's response, even resulting in different interpretations from the same words. For instance, hearing the word “hurry” spoken at a speaker's normal volume might do little to alter the listener's timeline while hearing the word “HURRY!” spoken at an inflated volume and with anxiety in the speaker's tone may cause the listener to drop everything and run.
Yet despite today's ubiquity of smart devices, their user interfaces can at best only understand semantic speech and, accordingly, are unable to comprehend let alone act upon the richer meaning conveyed by speech.